I discovered that I needed the diode, because prior to installing it, the engine wouldn't cut off when I shut the ignition switch off. The alternator was back feeding the circuit. When I unplugged the L terminal at that point, the car would shut off.

Yes, you should be able to wire switched 12v through the resistor (with diode - observe polarity), to the L terminal. Rough calculation is pretty simple here - 12/470 = 25 mA of current... Then I*V for power... .025*12v =.3 watts, so your resistor is ok.

The only upside for having the bulb (when installed per the diagram, will change the required resistor values) is that it tells you when the alternator is jacked - the bulb will light when the ignition is in the "on" position, with the alternator stopped, and when the alternator isn't functioning, but spinning.

 

So made a jumper with a led headlight bulb and the resister. Key on.. the bulb does not light up.. check power 12v…remove the jumper from L terminal and touch it to ground, boom lights up right away.. looks like my alternator is not providing ground.. assuming the 12v to L burnt out something inside.. I actually have my coworkers REW motor in the shop with an alternator on it. So I checked continuity to ground on his L terminal and it’s present where mine is not.. so do I have to get a new alternator or can I repair whatever’s wrong with it, also when I replace/fix the alt. I will have to add this led and resistor and hope it fixes it.. I really wish I could use my stock idiot light instead of adding all this **** in the harness, idk even kno where id put it

 

I swapped out my idiot cluster for a triple gauge pod, so I feel your pain.

As far as the alternator repair - swapping out the internal voltage regulator would be my first guess... never done it before though, so I can't offer any insight. They look like they're at least available from Rockauto, so hopefully a local parts store will have them too.

 

So come to find out my alt must be a Japanese version s5 or something.. what ever got an FD alt my pulley wouldn’t swap over, got a new pulley for it, and setup my jumper harness. Key on all my idiot lights turn on!! which would not happen previously… start it up and boom charging.. figured since my stock cluster lights now work I can eliminate the jumper. I did and it still worked!! The alt must ground a bunch of stuff. Any way very happy I don’t have to rev this thing any more. Fixed and upgraded in one move..
compounded and waxed the car after, now it’s a shiny terd lol. Now I need to replace my rear hatch cuz my defrost doesn’t work, someone pulled the grid off the glass, when they removed the tint, so can’t see **** in the morning.. the little things lol one at a time. I’m also looking for another fc like a mint one to either swap all this stuff over or to start a new build and use this as my beater

 

Had her out for the last month. Put in new seats and rails, a new head unit, and duct taped my windshield, so it wouldn't leak on my new seats lol. Lots left to do.. really need to get the tune cleaned up. Probly put a new set of spark plugs in before i put it away for the winter. Alternator still working great no more battery drain..